godot/thirdparty/icu4c/common/unifiedcache.cpp

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// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html
/*
******************************************************************************
* Copyright (C) 2015, International Business Machines Corporation and
* others. All Rights Reserved.
******************************************************************************
*
* File unifiedcache.cpp
******************************************************************************
*/
#include "unifiedcache.h"
#include <algorithm> // For std::max()
#include <mutex>
#include "uassert.h"
#include "uhash.h"
#include "ucln_cmn.h"
static icu::UnifiedCache *gCache = NULL;
static std::mutex *gCacheMutex = nullptr;
static std::condition_variable *gInProgressValueAddedCond;
static icu::UInitOnce gCacheInitOnce = U_INITONCE_INITIALIZER;
static const int32_t MAX_EVICT_ITERATIONS = 10;
static const int32_t DEFAULT_MAX_UNUSED = 1000;
static const int32_t DEFAULT_PERCENTAGE_OF_IN_USE = 100;
U_CDECL_BEGIN
static UBool U_CALLCONV unifiedcache_cleanup() {
gCacheInitOnce.reset();
delete gCache;
gCache = nullptr;
gCacheMutex->~mutex();
gCacheMutex = nullptr;
gInProgressValueAddedCond->~condition_variable();
gInProgressValueAddedCond = nullptr;
return TRUE;
}
U_CDECL_END
U_NAMESPACE_BEGIN
U_CAPI int32_t U_EXPORT2
ucache_hashKeys(const UHashTok key) {
const CacheKeyBase *ckey = (const CacheKeyBase *) key.pointer;
return ckey->hashCode();
}
U_CAPI UBool U_EXPORT2
ucache_compareKeys(const UHashTok key1, const UHashTok key2) {
const CacheKeyBase *p1 = (const CacheKeyBase *) key1.pointer;
const CacheKeyBase *p2 = (const CacheKeyBase *) key2.pointer;
return *p1 == *p2;
}
U_CAPI void U_EXPORT2
ucache_deleteKey(void *obj) {
CacheKeyBase *p = (CacheKeyBase *) obj;
delete p;
}
CacheKeyBase::~CacheKeyBase() {
}
static void U_CALLCONV cacheInit(UErrorCode &status) {
U_ASSERT(gCache == NULL);
ucln_common_registerCleanup(
UCLN_COMMON_UNIFIED_CACHE, unifiedcache_cleanup);
gCacheMutex = STATIC_NEW(std::mutex);
gInProgressValueAddedCond = STATIC_NEW(std::condition_variable);
gCache = new UnifiedCache(status);
if (gCache == NULL) {
status = U_MEMORY_ALLOCATION_ERROR;
}
if (U_FAILURE(status)) {
delete gCache;
gCache = NULL;
return;
}
}
UnifiedCache *UnifiedCache::getInstance(UErrorCode &status) {
umtx_initOnce(gCacheInitOnce, &cacheInit, status);
if (U_FAILURE(status)) {
return NULL;
}
U_ASSERT(gCache != NULL);
return gCache;
}
UnifiedCache::UnifiedCache(UErrorCode &status) :
fHashtable(NULL),
fEvictPos(UHASH_FIRST),
fNumValuesTotal(0),
fNumValuesInUse(0),
fMaxUnused(DEFAULT_MAX_UNUSED),
fMaxPercentageOfInUse(DEFAULT_PERCENTAGE_OF_IN_USE),
fAutoEvictedCount(0),
fNoValue(nullptr) {
if (U_FAILURE(status)) {
return;
}
fNoValue = new SharedObject();
if (fNoValue == nullptr) {
status = U_MEMORY_ALLOCATION_ERROR;
return;
}
fNoValue->softRefCount = 1; // Add fake references to prevent fNoValue from being deleted
fNoValue->hardRefCount = 1; // when other references to it are removed.
fNoValue->cachePtr = this;
fHashtable = uhash_open(
&ucache_hashKeys,
&ucache_compareKeys,
NULL,
&status);
if (U_FAILURE(status)) {
return;
}
uhash_setKeyDeleter(fHashtable, &ucache_deleteKey);
}
void UnifiedCache::setEvictionPolicy(
int32_t count, int32_t percentageOfInUseItems, UErrorCode &status) {
if (U_FAILURE(status)) {
return;
}
if (count < 0 || percentageOfInUseItems < 0) {
status = U_ILLEGAL_ARGUMENT_ERROR;
return;
}
std::lock_guard<std::mutex> lock(*gCacheMutex);
fMaxUnused = count;
fMaxPercentageOfInUse = percentageOfInUseItems;
}
int32_t UnifiedCache::unusedCount() const {
std::lock_guard<std::mutex> lock(*gCacheMutex);
return uhash_count(fHashtable) - fNumValuesInUse;
}
int64_t UnifiedCache::autoEvictedCount() const {
std::lock_guard<std::mutex> lock(*gCacheMutex);
return fAutoEvictedCount;
}
int32_t UnifiedCache::keyCount() const {
std::lock_guard<std::mutex> lock(*gCacheMutex);
return uhash_count(fHashtable);
}
void UnifiedCache::flush() const {
std::lock_guard<std::mutex> lock(*gCacheMutex);
// Use a loop in case cache items that are flushed held hard references to
// other cache items making those additional cache items eligible for
// flushing.
while (_flush(FALSE));
}
void UnifiedCache::handleUnreferencedObject() const {
std::lock_guard<std::mutex> lock(*gCacheMutex);
--fNumValuesInUse;
_runEvictionSlice();
}
#ifdef UNIFIED_CACHE_DEBUG
#include <stdio.h>
void UnifiedCache::dump() {
UErrorCode status = U_ZERO_ERROR;
const UnifiedCache *cache = getInstance(status);
if (U_FAILURE(status)) {
fprintf(stderr, "Unified Cache: Error fetching cache.\n");
return;
}
cache->dumpContents();
}
void UnifiedCache::dumpContents() const {
std::lock_guard<std::mutex> lock(*gCacheMutex);
_dumpContents();
}
// Dumps content of cache.
// On entry, gCacheMutex must be held.
// On exit, cache contents dumped to stderr.
void UnifiedCache::_dumpContents() const {
int32_t pos = UHASH_FIRST;
const UHashElement *element = uhash_nextElement(fHashtable, &pos);
char buffer[256];
int32_t cnt = 0;
for (; element != NULL; element = uhash_nextElement(fHashtable, &pos)) {
const SharedObject *sharedObject =
(const SharedObject *) element->value.pointer;
const CacheKeyBase *key =
(const CacheKeyBase *) element->key.pointer;
if (sharedObject->hasHardReferences()) {
++cnt;
fprintf(
stderr,
"Unified Cache: Key '%s', error %d, value %p, total refcount %d, soft refcount %d\n",
key->writeDescription(buffer, 256),
key->creationStatus,
sharedObject == fNoValue ? NULL :sharedObject,
sharedObject->getRefCount(),
sharedObject->getSoftRefCount());
}
}
fprintf(stderr, "Unified Cache: %d out of a total of %d still have hard references\n", cnt, uhash_count(fHashtable));
}
#endif
UnifiedCache::~UnifiedCache() {
// Try our best to clean up first.
flush();
{
// Now all that should be left in the cache are entries that refer to
// each other and entries with hard references from outside the cache.
// Nothing we can do about these so proceed to wipe out the cache.
std::lock_guard<std::mutex> lock(*gCacheMutex);
_flush(TRUE);
}
uhash_close(fHashtable);
fHashtable = nullptr;
delete fNoValue;
fNoValue = nullptr;
}
const UHashElement *
UnifiedCache::_nextElement() const {
const UHashElement *element = uhash_nextElement(fHashtable, &fEvictPos);
if (element == NULL) {
fEvictPos = UHASH_FIRST;
return uhash_nextElement(fHashtable, &fEvictPos);
}
return element;
}
UBool UnifiedCache::_flush(UBool all) const {
UBool result = FALSE;
int32_t origSize = uhash_count(fHashtable);
for (int32_t i = 0; i < origSize; ++i) {
const UHashElement *element = _nextElement();
if (element == nullptr) {
break;
}
if (all || _isEvictable(element)) {
const SharedObject *sharedObject =
(const SharedObject *) element->value.pointer;
U_ASSERT(sharedObject->cachePtr == this);
uhash_removeElement(fHashtable, element);
removeSoftRef(sharedObject); // Deletes the sharedObject when softRefCount goes to zero.
result = TRUE;
}
}
return result;
}
int32_t UnifiedCache::_computeCountOfItemsToEvict() const {
int32_t totalItems = uhash_count(fHashtable);
int32_t evictableItems = totalItems - fNumValuesInUse;
int32_t unusedLimitByPercentage = fNumValuesInUse * fMaxPercentageOfInUse / 100;
int32_t unusedLimit = std::max(unusedLimitByPercentage, fMaxUnused);
int32_t countOfItemsToEvict = std::max(0, evictableItems - unusedLimit);
return countOfItemsToEvict;
}
void UnifiedCache::_runEvictionSlice() const {
int32_t maxItemsToEvict = _computeCountOfItemsToEvict();
if (maxItemsToEvict <= 0) {
return;
}
for (int32_t i = 0; i < MAX_EVICT_ITERATIONS; ++i) {
const UHashElement *element = _nextElement();
if (element == nullptr) {
break;
}
if (_isEvictable(element)) {
const SharedObject *sharedObject =
(const SharedObject *) element->value.pointer;
uhash_removeElement(fHashtable, element);
removeSoftRef(sharedObject); // Deletes sharedObject when SoftRefCount goes to zero.
++fAutoEvictedCount;
if (--maxItemsToEvict == 0) {
break;
}
}
}
}
void UnifiedCache::_putNew(
const CacheKeyBase &key,
const SharedObject *value,
const UErrorCode creationStatus,
UErrorCode &status) const {
if (U_FAILURE(status)) {
return;
}
CacheKeyBase *keyToAdopt = key.clone();
if (keyToAdopt == NULL) {
status = U_MEMORY_ALLOCATION_ERROR;
return;
}
keyToAdopt->fCreationStatus = creationStatus;
if (value->softRefCount == 0) {
_registerPrimary(keyToAdopt, value);
}
void *oldValue = uhash_put(fHashtable, keyToAdopt, (void *) value, &status);
U_ASSERT(oldValue == nullptr);
(void)oldValue;
if (U_SUCCESS(status)) {
value->softRefCount++;
}
}
void UnifiedCache::_putIfAbsentAndGet(
const CacheKeyBase &key,
const SharedObject *&value,
UErrorCode &status) const {
std::lock_guard<std::mutex> lock(*gCacheMutex);
const UHashElement *element = uhash_find(fHashtable, &key);
if (element != NULL && !_inProgress(element)) {
_fetch(element, value, status);
return;
}
if (element == NULL) {
UErrorCode putError = U_ZERO_ERROR;
// best-effort basis only.
_putNew(key, value, status, putError);
} else {
_put(element, value, status);
}
// Run an eviction slice. This will run even if we added a primary entry
// which doesn't increase the unused count, but that is still o.k
_runEvictionSlice();
}
UBool UnifiedCache::_poll(
const CacheKeyBase &key,
const SharedObject *&value,
UErrorCode &status) const {
U_ASSERT(value == NULL);
U_ASSERT(status == U_ZERO_ERROR);
std::unique_lock<std::mutex> lock(*gCacheMutex);
const UHashElement *element = uhash_find(fHashtable, &key);
// If the hash table contains an inProgress placeholder entry for this key,
// this means that another thread is currently constructing the value object.
// Loop, waiting for that construction to complete.
while (element != NULL && _inProgress(element)) {
gInProgressValueAddedCond->wait(lock);
element = uhash_find(fHashtable, &key);
}
// If the hash table contains an entry for the key,
// fetch out the contents and return them.
if (element != NULL) {
_fetch(element, value, status);
return TRUE;
}
// The hash table contained nothing for this key.
// Insert an inProgress place holder value.
// Our caller will create the final value and update the hash table.
_putNew(key, fNoValue, U_ZERO_ERROR, status);
return FALSE;
}
void UnifiedCache::_get(
const CacheKeyBase &key,
const SharedObject *&value,
const void *creationContext,
UErrorCode &status) const {
U_ASSERT(value == NULL);
U_ASSERT(status == U_ZERO_ERROR);
if (_poll(key, value, status)) {
if (value == fNoValue) {
SharedObject::clearPtr(value);
}
return;
}
if (U_FAILURE(status)) {
return;
}
value = key.createObject(creationContext, status);
U_ASSERT(value == NULL || value->hasHardReferences());
U_ASSERT(value != NULL || status != U_ZERO_ERROR);
if (value == NULL) {
SharedObject::copyPtr(fNoValue, value);
}
_putIfAbsentAndGet(key, value, status);
if (value == fNoValue) {
SharedObject::clearPtr(value);
}
}
void UnifiedCache::_registerPrimary(
const CacheKeyBase *theKey, const SharedObject *value) const {
theKey->fIsPrimary = true;
value->cachePtr = this;
++fNumValuesTotal;
++fNumValuesInUse;
}
void UnifiedCache::_put(
const UHashElement *element,
const SharedObject *value,
const UErrorCode status) const {
U_ASSERT(_inProgress(element));
const CacheKeyBase *theKey = (const CacheKeyBase *) element->key.pointer;
const SharedObject *oldValue = (const SharedObject *) element->value.pointer;
theKey->fCreationStatus = status;
if (value->softRefCount == 0) {
_registerPrimary(theKey, value);
}
value->softRefCount++;
UHashElement *ptr = const_cast<UHashElement *>(element);
ptr->value.pointer = (void *) value;
U_ASSERT(oldValue == fNoValue);
removeSoftRef(oldValue);
// Tell waiting threads that we replace in-progress status with
// an error.
gInProgressValueAddedCond->notify_all();
}
void UnifiedCache::_fetch(
const UHashElement *element,
const SharedObject *&value,
UErrorCode &status) const {
const CacheKeyBase *theKey = (const CacheKeyBase *) element->key.pointer;
status = theKey->fCreationStatus;
// Since we have the cache lock, calling regular SharedObject add/removeRef
// could cause us to deadlock on ourselves since they may need to lock
// the cache mutex.
removeHardRef(value);
value = static_cast<const SharedObject *>(element->value.pointer);
addHardRef(value);
}
UBool UnifiedCache::_inProgress(const UHashElement* element) const {
UErrorCode status = U_ZERO_ERROR;
const SharedObject * value = NULL;
_fetch(element, value, status);
UBool result = _inProgress(value, status);
removeHardRef(value);
return result;
}
UBool UnifiedCache::_inProgress(
const SharedObject* theValue, UErrorCode creationStatus) const {
return (theValue == fNoValue && creationStatus == U_ZERO_ERROR);
}
UBool UnifiedCache::_isEvictable(const UHashElement *element) const
{
const CacheKeyBase *theKey = (const CacheKeyBase *) element->key.pointer;
const SharedObject *theValue =
(const SharedObject *) element->value.pointer;
// Entries that are under construction are never evictable
if (_inProgress(theValue, theKey->fCreationStatus)) {
return FALSE;
}
// We can evict entries that are either not a primary or have just
// one reference (The one reference being from the cache itself).
return (!theKey->fIsPrimary || (theValue->softRefCount == 1 && theValue->noHardReferences()));
}
void UnifiedCache::removeSoftRef(const SharedObject *value) const {
U_ASSERT(value->cachePtr == this);
U_ASSERT(value->softRefCount > 0);
if (--value->softRefCount == 0) {
--fNumValuesTotal;
if (value->noHardReferences()) {
delete value;
} else {
// This path only happens from flush(all). Which only happens from the
// UnifiedCache destructor. Nulling out value.cacheptr changes the behavior
// of value.removeRef(), causing the deletion to be done there.
value->cachePtr = nullptr;
}
}
}
int32_t UnifiedCache::removeHardRef(const SharedObject *value) const {
int refCount = 0;
if (value) {
refCount = umtx_atomic_dec(&value->hardRefCount);
U_ASSERT(refCount >= 0);
if (refCount == 0) {
--fNumValuesInUse;
}
}
return refCount;
}
int32_t UnifiedCache::addHardRef(const SharedObject *value) const {
int refCount = 0;
if (value) {
refCount = umtx_atomic_inc(&value->hardRefCount);
U_ASSERT(refCount >= 1);
if (refCount == 1) {
fNumValuesInUse++;
}
}
return refCount;
}
U_NAMESPACE_END